Studies in renal response to various protein intakes in preterm infants.

The renal effects of two diets--breast-milk and breast-milk with extra human protein (7 g/l breast-milk)--were compared in very low birth weight infants with a gestational age of 26 to 30 weeks. When the infants were given the high protein diet for one week the glomerular filtration rate (GFR) increased significantly more than when breast-milk alone was given. Sodium clearance showed a similar increase in proportion to the GFR during the two diets. The high protein diet raised the urine osmolality moderately in all individuals, while the diuresis remained unchanged. The data in the present study indicate that the function of the immature kidney is influenced by the amount of protein in the diet. However, the long-term renal effects in preterm infants maintained on a high protein intake remain unknown.